U.S. patent application number 10/705894 was filed with the patent office on 2004-11-25 for communication system.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Kamahori, Masao, Ohkawa, Takehiro, Takei, Ken, Yazawa, Yoshiaki, Yoshigi, Hiroshi.
Application Number | 20040233043 10/705894 |
Document ID | / |
Family ID | 33447562 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040233043 |
Kind Code |
A1 |
Yazawa, Yoshiaki ; et
al. |
November 25, 2004 |
Communication system
Abstract
A communication system is provided which enhances communication
stability, using chips on which function blocks are formed
including sensor, chip ID, and radio transmission/reception
functions. The sensor detects biological and chemical materials and
physical and stoichiometric quantities such as temperature,
pressure, and pH and the sensed results are transmitted to a reader
by a radio frequency (RF) function. The chip with the sensor
functions at a resonance frequency which is detected by the reader
initially during a frequency sweep. No dedicated power source is
essential to operate the chips, but instead the chips are triggered
into transmitting by the radio frequency signals transmitted from
the reader. The frequency and output of transmission from the
reader to the chips are variable. Stable communication can be
performed without being affected by variation in the chips
characteristics depending on manufacturing quality.
Inventors: |
Yazawa, Yoshiaki;
(Nishitokyo, JP) ; Kamahori, Masao; (Kokubunji,
JP) ; Takei, Ken; (Kawasaki, JP) ; Ohkawa,
Takehiro; (Tachikawa, JP) ; Yoshigi, Hiroshi;
(Hinode, JP) |
Correspondence
Address: |
REED SMITH LLP
3110 FAIRVIEW PARK DRIVE, SUITE 1400
FALLS CHURCH
VA
22042
US
|
Assignee: |
Hitachi, Ltd.
|
Family ID: |
33447562 |
Appl. No.: |
10/705894 |
Filed: |
November 13, 2003 |
Current U.S.
Class: |
340/10.3 ;
340/10.34; 340/10.41; 435/6.13 |
Current CPC
Class: |
G06K 19/0717 20130101;
G06K 19/0723 20130101 |
Class at
Publication: |
340/010.3 ;
340/010.34; 340/010.41; 435/006 |
International
Class: |
H04Q 005/22 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2003 |
JP |
2003-145610 |
Claims
What is claimed is:
1. A communication system comprising: a plurality of chips, each
including a sensor, a chip ID retaining circuit for retaining a
chip ID number, and a first resonance circuit; and a reader
comprising a second resonance circuit configured for carrying out
transmission and/or reception of data to or from said plurality of
chips, a frequency conversion circuit, and a chip ID compare
circuit for comparing said chip ID number of each said chip for a
match; wherein, based on said chip ID retaining circuit, said
frequency conversion circuit is configured to adjust carriers to a
resonance frequency which is optimum per said chip and which has
been obtained by a frequency sweep beforehand, and said reader is
configured to communicate with each of said chips at said resonance
frequency.
2. The communication system according to claim 1 wherein said
reader further comprises data storage for storing resonance
frequency information which stores a list of correspondence between
said chip ID number and said optimum resonance frequency.
3. The communication system according to claim 1, further
comprising an external control device which connects to said
reader, said external control device including data storage for
storing resonance frequency information and which stores a list of
correspondence between said chip ID number and said optimum
resonance frequency.
4. The communication system according to claim 1, wherein said
resonance frequency is determined separately for each of said chips
by said first resonance circuit on each of said chips.
5. The communication system according to claim 1, wherein said
resonance frequencies are determined separately for each of said
chips owing to circumstances around each said chip.
6. The communication system according to claim 1, wherein each of
said chips further comprises a radio frequency (RF) control unit
which comprises a rectification circuit, demodulation circuit, and
modulation circuit, a power supply control unit, a communication
control circuit, and a signal processing circuit, wherein said
signal processing circuit is configured to digitize signals
detected by said sensor; said demodulation circuit is configured to
compare said data received with said chip ID number retained by
said chip ID retaining circuit and demodulate said data; and
wherein said modulation circuit is configured to modulate the
digitized signals detected by said sensor; and the modulated
digital signals detected by said sensor are transmitted by radio
frequency (RF) to said reader.
7. The communication system according to claim 1, wherein said
sensor is configured to measure the quantity, temperature, or
pressure of an object to detect.
8. The communication system according to claim 1, further
comprising: a transport mechanism comprising piping and containers,
wherein said chips are installed in said transport mechanism and
said reader is placed outside said transport mechanism.
9. The communication system according to claim 8, wherein said
sensor is configured to detect the conditions of a liquid fluid
present inside said transport mechanism.
10. The communication system according to claim 8, wherein said
chips are configured to communicate with said reader and transmit
said chip ID number and measurements detected by said sensor; and
said chip ID number is corresponded to position information for
each of said chips.
11. The communication system according to claim 8, wherein sections
of said piping where said chips are installed have lower
conductivity than other sections.
12. The communication system which is applied to the transport
mechanism according to claim 8, wherein sections of said piping
where said chips are installed have through holes and cores are
inserted in said through holes.
13. The communication system according to claim 8, wherein said
chips are supplied with required electric power by radio frequency
transmission from said reader.
14. The communication system which is applied to the transport
mechanism according to claim 8, further comprising: an external
control device which is installed outside said transport mechanism,
a transceiver connected to said external control device, a
transceiver antenna connected to said transceiver, and a reader
antenna connected to said reader, wherein said reader is provided
with an additional long-range communication function and
communicates with said external control device via said reader
antenna, said transceiver antenna, and said transceiver.
15. A communicating reader comprising a resonance circuit, an
oscillator, and a radio frequency control unit which includes a
frequency conversion circuit, wherein said resonance circuit and
said oscillator carries out signal transmission and reception for
communication with chips and a frequency sweep for said chips; and
said frequency conversion circuit is configured to convert a
transmitting frequency to each of said chips to a resonance
frequency for communication with each of said chips, based on said
frequency sweep.
16. The communicating reader according to claim 15, further
comprising a chip ID compare circuit which retains chip ID codes
independently retained on said chips and compares said chip ID
codes for a match.
17. The communicating reader according to claim 15, further
comprising a mechanism for controlling the strength of signals to
be transmitted to said chips, according to the strength of signals
received from said chips.
18. A communication method comprising: transmitting from a reader
information containing a chip ID code while performing a frequency
modulation; detecting in a chip whether there is a match between
said chip ID code transmitted from the reader and a chip ID number
unique to said chip; and transmitting from said chip a result of
detecting said match signals detected by a sensor included on said
chip to said reader, wherein, in said detecting step, said chip
compares both of said chip ID code and said chip ID number for a
match during said frequency modulation.
19. The communication method according to claim 18, wherein said
information transmitting step and said detecting step are repeated
until a match between both of said ID codes is detected.
20. The communication method according to claim 18, wherein a
plurality of chips are used and each of said chips detects whether
there is a match between said chip ID code received from said
reader and said chip ID number unique to each of said chips.
Description
PRIORITY CLAIM
[0001] This application claims priority to Japanese patent
application P2003145610 filed May 23, 2003, the entire disclosure
of which is hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a communication system
which transmits the results of detection of biological materials
such as nucleic acids, proteins, antigens, and antibodies and the
measurements of physical and stoichiometric quantities such as
temperature, pressure, light, and ion concentration to external
equipment in a non-contact manner.
[0004] 2. Description of Related Art
[0005] With the findings of genome sequences and the development of
gene analysis technology, in recent years, accumulation of
knowledge on associating diseases and drug sensitivity with genes
has augmented rapidly. Using such information, by investigating
gene expression under various conditions and gene mutation in a
variety of organisms, the functions of genes and the association of
genes with diseases and sensitivity to drugs and medicines are
identified and it is being revealed how gene expression networks
and single nucleotide polymorphisms (SNPs) in genes have relation
to a particular illness and constitution.
[0006] When diagnosing diseases, using gene information, gene
inspection is believed to be typing of known genes and their
mutations. While techniques for processing large quantities of
samples at a high speed are required in seeking unknown genes and
mutations, an inspection process which can easily be performed for
relatively small quantities of samples at low cost is desirable for
typing and several methods for achieving such a process have been
devised. As a system that can be used for SNPs analysis and gene
inspection, for example, a microarray system has been reported (for
example, Non-Patent Document Cited 1, Nature Gent. 18, 91
(1998).
[0007] In a microarray, spotting diverse oligo-DNAs or cDNAs on
glass slides coated with poly-L-lysine is performed. Spotting is
performed by a spotter which can form spots with dozens of
micrometers to 200 .mu.m in diameter at a pitch of 100-500 .mu.m.
After spotting, the samples on the glass slides are post processed
and dried and kept intact at room temperature. For target sample
preparation, RNA is extracted from a sample cell and, from the RNA,
cDNA labeled by fluorescent dye such as Cyanine3 and Cyanine5 is
prepared. The target sample solution is dropped on the above
microarray and the microarray is incubated for about 10 hours at
65.degree. C. in a moisture chamber. After the completion of
hybridization, the microarray is washed with a 0.1% SD solution and
dried at room temperature. For assaying the microarray, a scanner
is used. As a light source for excitation, for example, an argon
ion laser is used. As an emission detector, for example, a
photomultiplier tube is used. Using confocal optics, the influence
of background light in the periphery of the focal point is
eliminated and the S/N ratio is enhanced. To assay fluorescent
emission from many spots, it is necessary to position the
microarray to the reading optics with high precision. Thus, a
translational stage which allows for translational movement within
an error of dozens of micrometers is built into the scanner.
[0008] Also, an antenna and card-form storage medium assembly for
writing and reading of data in a non-contact manner has been
reported (for example, Patent Document Cited 1, JP-A No.
165132/2000). This assembly includes means for converting load
resistance which converts the load resistance of electronic
circuitry from the perspective of the antenna to a predetermined
value. By the load resistance converting means, the maximum
electromotive force is supplied to the electronic circuitry
connected, thereby making the electronic circuitry always operate
logically and efficiently.
[0009] [Patent Document Cited 1]
[0010] JP-A No. 165132/2000
[0011] [Non-Patent Document Cited 1]
[0012] Nature Gent. 18, 91 (1998)
[0013] As for the DNA microarray which attracts attention as a gene
inspection method, because the quantities and shapes of the spotted
solutions lead to variation in the measurements of fluorescence
intensity in the assay process, performance of forming highly
uniform spots is important. In practical operation, however, such
variation in the measurements due to non-uniform spots was not
avoidable.
[0014] As for the antenna and card-form storage medium assembly for
writing and reading of data in a non-contact manner disclosed in
Patent Document Cited 1, the card-form storage medium assembly
includes the means for converting the load resistance of electronic
circuitry from the perspective of the antenna to a predetermined
value, but it was not able to overcome card-by-card resonance
frequency variation due to variation in manufacturing the card-form
storage media.
SUMMARY OF THE INVENTION
[0015] The present invention uses miniature chips, each of which
comprises a sensor which detects the quantity of a target of a type
which differs per chip or related physical and stoichiometric
quantities such as temperature and pressure, circuit blocks having
different functions of signal processing to manipulate sensed data,
non-contact communication control, retaining chip ID number and ID
comparison, and power supply generation and control, a coil for
communicating with an external control device, and capacitance. The
chips are installed to be in contact with different sample
solutions and each chip detects the quantity of a target of a type
which differs per type or related physical and stoichiometric
quantities such as temperature and pressure and converts a signal
detected into a digital electric signal. On the other hand, an
external reader transmits a chip ID code to identify a particular
chip out of a plurality of chips, using means of transmission which
may be electromagnetic waves, change in a magnetic field, or change
in an electric field.
[0016] Between the foregoing reader/writer and a micro-transponder
consisting of a transponder provided with a sensor, information
about chemical reaction obtained by a probe appropriate for the
object to be detected is transmitted from the transponder to the
external reader/writer and several methods are possible to carry
out such transmission by wireless means. Although several media are
possible to be used for the transmission methods, focusing on that
the reader/writer performs information processing electrically,
according to a journal that provides relevant information, when
consistency with circuitry is considered, the use of
electromagnetic waves as a transmission medium is advantageous in
cost reduction, in comparison with, for example, a method in which
ultrasonic waves are used as a transmission medium, because the use
of electromagnetic waves can dispense with new converters for
conversion of ultrasonic waves to electrical signals and vice
versa.
[0017] There are three basic modes of transmission of
electromagnetic waves in free space: near field, inductive field,
and radiation field. Even if information is transmitted on
electromagnetic waves, the system configuration and the structures
of constituent devices greatly change, depending on which of the
above three modes is used. For the system using the radiation
field, radio interfaces between the transponder and the
reader/writer are antennas and usable frequencies are limited to
make the antenna efficiency sufficiently great. If the dimensions
of the transponder are a few square millimeters (1.times.1 mm.sup.2
to 3.times.3 mm.sup.2), radiation efficiency is assumed to be about
-20 dB if 1 GHz is used and about -10 dB if 10 GHz is used. To
prevent the influence of external noise, it is necessary to select
a frequency band of the order of 10 GHz. Even with the state of art
semiconductor technology, semiconductor integration technology is
not sufficient to fabricate such a small chip. Thus, transponders
as small as a few square millimeters are impossible to realize or
high cost devices even if they can be produced and the problem of
prior art cannot be resolved. Use of the near field, in electrical
circuitry, a capacitor is formed between the transponder and the
external control device and information is transmitted in the radio
space, taking advantage of change in electric charges in the
capacity. Accordingly, the electric charges which carry information
must be localized in correct position. In principle, it is
impossible to hold down increase in the manufacturing cost
regarding the accuracy of charge localization and, consequently,
the problem of prior art cannot be resolved. In the spatial
transmission of information using the inductive field, information
is transmitted, taking advantage of energy movement produced by a
transformer which is formed between the coil of the transponder and
the coil of the reader/writer. A magnetic field generated by the
primary coil of the transponder is captured by the coil of the
reader/writer and the resulting magnetic path functions as the
transmission path through which communication is performed. Because
of the property of magnetic field energy that is ubiquitous broadly
in space, in principle, positional relationship between the
transponder and the reader/writer does not require high accuracy.
Once the magnetic path has been formed in the inductive field,
information is transmitted along the magnetic path, or in other
words, through the unspread channel. Thus, the use of the inductive
field can significantly enhance the efficiency of transmitting
energy to the external space, as compared with the mode of using
the radiation field in which electromagnetic waves are radiated
broadly in space by the antennas. Therefore, when using
electromagnetic waves as the medium of transmitting information
between the transponder and the reader/writer, selecting the
inductive field is advantageous in order to solve the problem of
prior art.
[0018] In order to obtain a good efficiency of transmitting
information by radio, using the inductive field, the following
points should be noted. First, due to variation in manufacturing
transponders and depending on the circumstances where the
transponders are placed, the resonance frequency of the
transponders may shift and stable communication must be performed
without being affected by such a shift. The resonance frequency
greatly varies, depending on the components of a resonance circuit
such as the coil, capacitance, and resistors of the transponder
and, in addition, the presence of other conductors located outside
the transponder. Although it is possible to adjust the resonance
frequency by trimming, it is undesirable to add such a process to
the transponder manufacturing process because doing these increases
the cost and such adjustment is ineffective for change due to the
circumstances around the transponder when measurements are taken.
The magnetic path during actual measurement may change, depending
on the positional relationship between the transponder's coil and
the coil of the reader/writer. Communication may become impossible
when the transponder and the reader/writer are placed in
circumstances of worse conditions than the positional relationship
expected in the design phase, whereas breakdown of the transponder
may occur by excessive power generated when the transponder is in
closer proximity to the reader/writer than expected in the design
phase. Thus, without exerting high precision control of relative
positional relationship between both coils, it is essential to
provide means for enabling stable communication which produces an
equivalent effect to such control.
[0019] In order to carry out stable communication without being
affected by shifts in the resonance frequency of the
above-mentioned chips as transponders, the frequency at which the
magnetic field that is generated in the reader changes is set
variable, according to the resonance frequency of the chip to
communicate with. To find the resonance frequency of an individual
chip, a frequency sweep is first performed for the chips. In the
frequency sweep, first, the reader sends changing frequency bands
to the chips. Then, the chips reply at their optimum resonance
frequencies and return their chip IDs to the reader at their
optimum resonance frequencies. The reader relates the optimum
frequency to the chip ID (ID number) for each chip and stores the
correspondence between the optimum frequency to the chip ID (ID
number). This correspondence may be stored on the reader itself or
on external means (data storage etc.) for storing information.
After the frequency sweep, the reader communicates with the chips
at the optimum frequencies per chip.
[0020] The above is required for the following reason. During the
process of manufacturing the internal coils of the chips and the
input/output impedances of rectification, detection, and other
circuits connected to the internal coil on each chip, the
individual chips may come to have different optimum resonance
frequencies in a dispersion range. By incorporating the
above-described means into the invented system, communication
between the reader and the chips can be performed at optimum
frequency bands per chip, accommodating variation in the resonance
frequency per chip. Concretely, to enhance the stability of
communication, the frequency at which the external control circuit
uses for transmission is varied over time and, accordingly, a
magnetic path is formed by magnetic flux generated by the magnetic
path and signals are transmitted and received through the magnetic
path. Manufacturing variation of the internal coil and
manufacturing variation of input and output impedances of circuits
such as rectification and detection connecting to the internal coil
reflect on variation in the frequency characteristics in the
impedance matching state of the internal coil and the circuits such
as rectification and detection. Because the shape and size of the
external coil of the reader (or external control device) can
usually be ten times as much as the shape and size of the internal
coil, change in the matching state of the external coil and the
circuits of the reader such as rectification and detection due to
external coil size variation is negligibly small as compared with
the case of the internal coil. Therefore, the frequency that is
used for forming a magnetic path between the reader and chip, in
other words, used for communication is varied over a suitable
frequency band and a magnetic path is formed by magnetic flux
generated by the external coil and signals are transmitted and
received through the magnetic path. For a plurality of chips,
communication at a suitable frequency is effected by which a good
matching state specific to each chip internal coil and circuits
such as rectification and detection takes place. In this way, a
magnetic path can be formed efficiently between the internal coil
and external coil, thus avoiding lowering communication stability
by chip manufacturing variation. In other words, a problem of
signal deterioration caused by energy generated when a magnetic
path is formed by magnetic flux generated by the external coil,
which is caused by chip manufacturing variation, need not be
considered in the system. Thus, the allowance range of chip
manufacturing variation can be extended and, consequently, chip
manufacturing cost can be curtailed greatly.
[0021] In the present invention, to enhance the probability that a
magnetic path is formed between the internal coil mounted on the
chip and the external coil of the reader (or external control
device), the reader (or external control device) repeats, by a
plurality of times, a process which comprises generating magnetic
flux by the external coil, forming a magnetic path, transmitting
and receiving signals through the magnetic path. This is easily
implemented by repeating signal processing using the external coil
of the reader (or external control device) by a plurality of
times.
[0022] In the present invention, with fluctuation in electric power
excited on the chip, according to positional relationship between
the chip's coil and the reader's coil, chip breakdown if the
distance between both coils becomes too short is prevented. For
this purpose, the reader controls RF output while monitoring the
output of signals from the chips. Even for a chip whose distance
from the reader greatly diverges from its normal position, stable
signal reading can be performed.
[0023] Communication stability also varies, depending on the
magnetic path during actual measurement, that is, the positional
relationship between the chip's coil and the reader's coil. To
enhance communication stability and prevent chip breakdown by
excessive electric-power generated when the chip and reader come in
mutual close proximity, it is advisable to adjust current amperage
flowing across the reader's coil while monitoring the signals from
the chips.
[0024] According to the present invention, a simple communication
system without requiring peripheral devices can be provided at a
low cost. As a solution to resonance frequency variation per chip
due to variation in manufacturing the chips and depending on the
circumstances where the chips are placed, for example, buffer
solutions including different samples, other chips, or reaction
containers exist around a chip, by adjusting the carrier frequency
to the resonance frequency of the chip to communicate with,
communication can be stabilized. Each chip transmits the result of
comparing the chip ID number retained on the chip with sensed data
from raw data detected by the sensor of the chip to the reader, and
communication of data compared with the chip ID number can be
performed stably. When measurements are taken with a plurality of
chips having different sensor functions, a diverse range of
measurements of materials can be taken and checked substantially at
a time and quickly.
[0025] The invented communication system enables in-situ inspection
for a variety of objects at hospitals without a specialized
inspection department, general hospitals which are not contracted
inspection agencies, food factories, food-providing agencies, and
distribution agencies.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic diagram showing a communication system
configuration example according to Embodiment 1 of the present
invention;
[0027] FIG. 2 is a schematic diagram showing a communication system
configuration example according to Embodiment 2 of the present
invention;
[0028] FIG. 3 is a schematic diagram showing a communication system
configuration example according to Embodiment 3 of the present
invention;
[0029] FIG. 4 is a diagram showing an example of a time sequential
procedure of transmitting data between the reader and the chip
according to Embodiment 4 of the present invention;
[0030] FIG. 5 is a diagram showing an example of a time sequential
procedure of transmitting data between the reader and the chip
according to Embodiment 5 of the present invention;
[0031] FIG. 6 is a schematic diagram showing a reader configuration
example featuring signal peak detection and output control,
according to Embodiment 6 of the present invention;
[0032] FIG. 7 is a schematic showing a measurement system
application example to a plant, according to Embodiment 7 of the
present invention, as a communication system configuration example
for wirelessly measuring liquid conditions in a pipe, using chips
installed inside the pipe and a reader installed outside the
pipe;
[0033] FIG. 8 is a schematic showing a communication system
configuration example in which the passage of magnetic lines of
force is provided in a chip installation position, according to
Embodiment 7 of the present invention;
[0034] FIG. 9 is a schematic showing a communication system
configuration example which performs monitoring of a plurality of
pipings over a long distance and in which chips are installed in
pipes and readers and coils are installed outside and near the
pipes, the readers featuring a wireless communication function,
according to Embodiment 8 of the present invention; and
[0035] FIG. 10 is a schematic showing a communication system
configuration example which performs monitoring of a plurality of
synthetic reaction baths over a long distance and in which chips
are installed inside synthetic reaction baths and readers and coils
are installed outside and near the baths, the readers featuring a
wireless communication function, according to Embodiment 8 of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] [Embodiment 1]
[0037] A preferred Embodiment 1 of the present invention will now
be described with reference to FIG. 1. FIG. 1 is a schematic
diagram showing the structures of the electric circuitry blocks of
a reader and a chip in a measurement system of the present
invention. The reader 101 is comprised of a radio frequency (RF)
interface block (RF control unit, and the same will apply
hereinafter) 104, an oscillator block 107, a communication control
circuit block 103, and an external coil 105. The reader is
controlled b an application control block 102. The RF interface
block is a circuit block having RF signal transmission and
reception functions. Carriers generated by the oscillator 107,
after being modulated by a signal generated by the communication
control circuit, are amplified by an output amplifier, according to
an output variable function, and fed to the external coil of the
reader.
[0038] The chip is comprised of an internal coil 205, a capacitor
206 which is a component of a resonance circuit, an RF interface
204, a power supply regulator 202, a communication control circuit
203, a chip ID retaining circuit 208, a signal processing circuit
207, and a sensor 209. Change in the magnetic flux generated by the
external coil is received by the internal coil of the chip, passed
through a rectification circuit, stabilized by the power regulator
block, and used as the power supply for driving the circuit blocks
in the chip. A signal transmitted from the reader is demodulated by
the RF interface 204, passed to the communication circuit 203,
undergoes an ID compare sequence in which the chip ID number part
of the signal is compared with the chip ID number retained by the
chip ID retaining circuit 208, and, only when both ID number match,
the signal is used to control the sensor. From the chip, sensed
data digitized through the signal processing circuit 207 and the
result of comparing the received chip ID number with the chip ID
number retained by the chip ID retaining circuit 208 are passed
through the communication control circuit 203, modulated by the RF
interface 204, and transmitted to the reader by modulating the load
of the coil 205.
[0039] It is assumed that the reader communicates with a plurality
of chips. To stabilize such communication, it is required that the
chips have a constant resonance frequency. However, due to
variation in manufacturing the chips and depending on the
circumstances where the chips are placed, for example, buffer
solutions including different samples, other chips, or reaction
containers exist around a chip, it is inevitable that the resonance
frequency varies per chip. Resonance frequency difference due to
variation in manufacturing the chips can be adjusted to a
predetermined resonance frequency by trimming the capacitance of an
individual chip. However, trimming increases the chip cost and is
ineffective for resonance frequency variation depending on the
circumstances around an individual chip. To overcome this problem,
the RF interface 104 of the reader 101 is provided with a frequency
variable function. Using this function, the frequency of the
oscillator 107 is varied to adjust the carrier frequency to the
resonance frequency of the chip to communicate with during
measurement, so that the communication can be stabilized.
[0040] To stabilize the communication, frequency sweep is performed
for the chips when initiating the communication. For example, if
communication is to be performed at 13.56 MHz, a 12-18 MHz
frequency band range is transmitted from the reader. Individual
chips reply at an optimum frequency selected out of the swept
frequency band and return the chip ID information to the reader,
using the optimum frequency. The reader relates the return signal
frequency from the chip to the chip ID for each chip and thus
detects the resonance frequency corresponding the communication of
each individual chip. The thus obtained correspondences of the IDs
of the chips and the frequencies for communication with the chips
can be stored on an external ROM or RAM of the application control
unit so that the correspondences can be referenced when initiating
communication with the chips again.
[0041] There are two main methods of frequency sweep. One method is
to transmit pulses of electromagnetic waves of different
frequencies in sequence; for example, in order of 13.56, 14.0,
14.5, 15.0 MHz, etc. Actually, if a frequency is used as a main
carrier, the main frequency has predetermined side bands. If
selected main frequencies are modulated by 0.5 MHz and the
modulated pulses are transmitted, in consequence, a sweep over a
substantially continuous frequency band can be performed. The other
method is to transmit electromagnetic waves of continuous
frequencies in a band; for example, continuous frequencies from 12
MHz to 8 MHz. In Embodiment 1, the frequency sweep is performed,
using the second method. In other embodiments of the invention
which will be described hereinafter, the frequency sweep is assumed
to be performed in the same manner.
[0042] According to the above-described method, trimming for
adjusting the resonance points of the chips is unnecessary and,
therefore, the communication system of the invention can keep a lid
on costs of the chips. Also, the communication system of the
invention can dynamically accommodate resonance point shifts
occurring, depending on the surroundings of the chips.
[0043] [Embodiment 2]
[0044] A concrete embodiment of the present invention will be
described with reference to FIG. 2. FIG. 2 is a schematic diagram
illustrating the function blocks of the reader and the chip
according to the present invention. On the reader, a chip ID
compare circuit 109 and a retransmission control circuit 110 are
installed and a frequency-variable oscillator 107 including series
internal resistance 108, wherein the oscillation frequency can be
varied by a frequency conversion circuit 111 which operates by a
control signal issued from a communication control circuit 121, an
external coil 105, and external resonance capacitance 106 are
connected in parallel and installed. Inside a chip 201, a circuit
in which an internal coil 205 and internal resonance capacitance
206 are connected in parallel, a sensor 209, a detection and
rectification circuit 211, a modulation/demodulation circuit 212, a
communication control circuit 203, a signal processing circuit 207,
an ID verify and sensed data forward circuit 214, a power supply
circuit 210, an analog-digital converter (ADC) 213, and a chip ID
retaining circuit 208 are installed. In the circuitry of the chip,
the circuit in which the internal coil 205 and internal resonance
capacitance 206 are connected in parallel connects to the detection
and rectification circuit 211, the rectified output of the
detection and rectification circuit 211 is supplied to the power
supply circuit 210, the detection and rectification circuit 211
connects to the modulation/demodulation circuit 212, the
modulation/demodulation circuit 212 connects to the communication
control circuit 203, and the communication control circuit 203
connects to the signal processing circuit 207, the signal
processing circuit 207 connects to the ID verify and sensed data
forward circuit 214, the ID verify and sensed data forward circuit
214 connects via the ADC 213 to the sensor 209, the chip ID
retaining circuit 208 connects to the ID verify and sensed data
forward circuit 214, and the detection and rectification circuit
211, modulation/demodulation circuit 212, communication control
circuit 203, signal processing circuit 207, ID verify and sensed
data forward circuit 214, ADC 213, and sensor 209 are supplied with
required power from the power supply circuit 210. Supplying power
from the reader 101 to the chip 201 and transmitting data between
the reader and the chip are performed through a magnetic path which
is formed by magnetic flux generated by both the external coil 105
and the internal coil 205. The reader 101 reads a chip ID code
which is required from the chip ID compare circuit 109. After
proper modulation is performed, a carrier frequency fit for the
chip ID code is selected, and the frequency-variable oscillator 107
generates an RF signal at the selected frequency under the control
of the frequency conversion circuit 111. The RF signal having the
chip ID and other data modulated thereon is supplied to a parallel
resonance circuit consisting of the external coil 105 and external
resonance capacitance 106. The external coil emits magnetic flux
into space and this magnetic flux is captured by the chip's
parallel resonance circuit consisting of the internal coil 205 and
internal resonance capacitance 206 and the RF signal is transmitted
to the detection and rectification circuit 211. The RF signal is
rectified and its rectified output is accumulated in the power
supply circuit 210 from which the thus accumulated power is
supplied to other electronic circuits within the chip 201 and the
sensor. On the other hand, the detected output from the detection
and rectification circuit is demodulated by the
modulation/demodulation circuit 212 and the chip ID code generated
by the reader is reproduced by the communication control circuit
203 and signal processing circuit 207. The ID verify and sensed
data forward circuit 214 compares this reproduced chip ID code with
the chip ID number which is unique to the chip and retained by the
chip ID retaining circuit 208 and a sequence of operation is
repeated until both ID codes match. Only after verifying a match
between the chip ID code generated by the reader and the chip ID
number which is unique to the chip and the chip holds it in the
chip ID retaining circuit 208, information sensed by the sensor 209
is input via the ADC 213 to the ID verify and sensed data forward
circuit 214. The information is transferred via the signal
processing circuit 207 and communication control circuit 203 to the
modulation/demodulation circuit 212. After the information is
modulated properly by the modulation/demodulation circuit into a
signal having the data modulated thereon, the signal is passed
through the detection and rectification circuit 211 and supplied as
an RF signal to the parallel resonance circuit consisting of the
internal coil 205 and internal resonance capacitance 206. The
internal coil emits magnetic flux into space and this magnetic flux
is captured by the reader's parallel resonance circuit consisting
of the external coil 105 and external resonance capacitance 106 and
the RF signal is transmitted to the reader 101. The above-described
procedure is repeated a plurality of times at intervals of given
time which is determined by the retransmission control circuit 110
built in the reader 101. In the measurement system of the present
invention, a sufficient amount of electric energy must be
transmitted from the reader to the chip through the magnetic path
which is formed by the magnetic flux produced between the external
coil integrated into the reader and the internal coil included in
the chip. Therefore, a sequence of operation of RF signal
transmission at a single frequency generated by the
frequency-variable oscillator under the control of the frequency
conversion circuit must be performed for sufficiently long time and
an optimum number of times of retransmission relative to the level
of accuracy at which the measurement system takes measurements must
be selected by the retransmission control device. Because the
reader acquires measurement results data by radio from chips having
specific ID codes, the properties of materials of many kinds can be
measured with a plurality of chips having different sensor
functions and a diverse range of measurements of the materials can
be taken and checked substantially at a time and quickly. Using a
plurality of chips having different sensor functions or a plurality
of chips having sensors to detect different objects, a plurality of
substances existing in an analyte can be checked substantially at a
time and quickly.
[0045] [Embodiment 3]
[0046] Another preferred embodiment of the present invention will
be described, using FIG. 3. FIG. 3 is a schematic diagram showing
electric circuitry of a reader in a measurement system of another
embodiment of the present invention. This reader differs from the
reader of Embodiment 2 shown in FIG. 2 in the following respects.
Additionally, a frequency variable range control circuit 112
connects to the communication control circuit 121 and a current
detector 113 is inserted in series across one of the lines which
make parallel connection of the parallel circuit consisting of the
internal coil 205 and internal resonance capacitance 206 and the
series circuit consisting of the frequency-variable oscillator 107
and internal resistance 108. Using a signal detected by the current
detector as an input control signal, the frequency variable range
control circuit generates a control signal to dynamically change
the frequency variable range and supplies this signal to the
frequency conversion circuit 111. In the measurement system of the
present invention, in order to transmit a sufficient amount of
electric energy from the reader to the chip, a sequence of
operation of RF signal transmission at a single frequency generated
by the frequency-variable oscillator under the control of the
frequency conversion circuit must be performed for sufficiently
long time. However, because the internal coil and internal
resonance capacitance within a chip are generally small and need to
be produced at low cost, it is difficult to adjust their electrical
characteristics uniformly. Frequency at which the chip's parallel
resonance circuit consisting of the internal coil and internal
resonance capacitance is electromagnetically coupled to the
reader's parallel resonance circuit consisting of the external coil
and external resonance capacitance most efficiently varies,
depending on the manufacturing quality of the chip's parallel
resonance circuit part. By varying the frequency of the magnetic
flux generated by the external coil of the reader, transmission and
reception of data and energy between the reader and the chip at the
frequency at which the chip's parallel resonance circuit consisting
of the internal coil and internal resonance capacitance is
electromagnetically coupled to the reader's parallel resonance
circuit consisting of the external coil and external resonance
capacitance most efficiently can be realized. In this relation, it
is desirable to cut off transmission and reception of data and
energy between the reader and the chip at frequencies other than
the frequency at which the chip's parallel resonance circuit
consisting of the internal coil and internal resonance capacitance
is electromagnetically coupled to the reader's parallel resonance
circuit consisting of the external coil and external resonance
capacitance most efficiently. At the frequency at which the chip's
parallel resonance circuit consisting of the internal coil and
internal resonance capacitance is electromagnetically coupled to
the reader's parallel resonance circuit consisting of the external
coil and external resonance capacitance most efficiently, the
current detector output becomes great. Therefore, the output of the
current detector is monitored by the frequency variable range
control circuit and, in a range of frequencies generated by the
frequency-variable oscillator controlled by the frequency
conversion circuit, a frequency region for which the current
detector output is relatively low is cut in steps. In consequence,
time required for the measurement system to complete one cycle of
measurement can be shortened. In the present embodiment,
transmitting energy from the reader to the chips and transmitting
data between the reader and the chips are not performed in an
inefficient frequency region. Therefore, the following advantageous
effects are obtained: time to be taken for the measurement system
to take measurements is shortened and the power consumed by the
system is reduced.
[0047] [Embodiment 4]
[0048] Yet another preferred embodiment of the present invention
will be described, using FIG. 4. FIG. 4 shows a time sequential
procedure of transmitting data between the reader (device) and the
chip in the measurement system of another embodiment of the present
invention. As regards frequency sweep in this embodiment
illustrated in FIG. 4, one of the above-mentioned methods, that is,
the method of transmitting electromagnetic waves of frequencies in
given steps is used, and frequencies in 0.5-MHz steps in a
predetermined range are transmitted from the reader when a
frequency sweep is performed. First, the reader transmits data of
chip ID code 1 to the chip, using magnetic flux at frequency f1.
Then, the chip determines whether the chip ID code matches the ID
number unique to the chip: If the chip ID code data from the reader
does not arrive at the chip, the chip regards it as arrival of null
data of chip ID code and determines that chip ID code 1 does not
match the ID number unique to the chip. As described for Embodiment
2 of FIG. 2, after the repetition of transmission at the same
frequency for sufficiently long time, the frequency of magnetic
flux generated from the reader is changed to f2 (from f1) and, on
the chip, comparing the received chip ID code with the ID number
unique to the device (chip) is repeated. Once the above process has
been terminated, the same process is repeated by a suitable number
of times. During the repetition, when it has been detected that the
chip ID code received by the measuring device (chip) matches the ID
code unique to the device, the chip converts information from the
sensor to sensed data and transmits the sensed data through
magnetic flux generated by the internal coil to the reader.
According to the present embodiment, the reader can selectively
acquire only data from the chip which is sensing information that
the reader operator wishes to get. In other words, the reader can
identify data that a chip has, such as measurements taken by the
sensor of the chip, from the chip ID code, and can acquire the data
selectively. It can be checked in a non-contact manner whether a
liquid sample has a specific property or includes a specific
substance, wherein the liquid sample is measured by the chip
situated in place.
[0049] [Embodiment 5]
[0050] A further preferred embodiment of the present invention will
be described, using FIG. 5. FIG. 5 shows a time sequential
procedure of transmitting data between the reader and the chip in
the measurement system of another embodiment of the present
invention. First, the reader transmits data of chip ID code 1 to
the chip, using magnetic flux at frequency f1. Then, the chip
determines whether the chip ID code matches the ID number unique to
the chip. If the chip ID code data from the reader does not arrive
at the chip, the chip regards it as arrival of null data of chip ID
code and determines that chip ID code 1 does not match the ID
number unique to the chip. As described for Embodiment 2 of FIG. 2,
after the repetition of transmission at the same frequency for
sufficiently long time, the frequency of magnetic flux generated
from the external control device is changed to f2 (from f1) and, on
the chip, comparing the received chip ID code with the ID code
unique to the device (chip) is repeated. During this process,
relationship between a value detected by the current detector built
in the reader and frequency being used for transmission is stored
and the frequency variable range in which the frequency conversion
circuit controls the frequency to be generated by the variable
frequency oscillator is changed by the frequency variable range
control circuit, when appropriate, so that the reader does not
generate magnetic flux in a frequency region for which the current
detector detects a relatively low value. As described above, due to
variation in manufacturing the chips and depending on the
circumstances where the chips are situated, for example, buffer
solutions including different samples, other chips, or reaction
containers exist around a chip, it is inevitable that the resonance
frequency varies per chip. To overcome this problem, a signal
detected by the current detector, based on which a control signal
is generated to dynamically change the frequency variable range in
which the oscillator of the reader generates frequencies, is
related to the chip ID code and this correspondence is stored.
Referring to this correspondence data, the reader varies the
oscillator frequency to adjust the carrier frequency to the
resonance frequency of the chip, according to the chip to
communicate with, and, thereby, communication can be stabilized.
The above process is repeated by a number of times determined by
the retransmission control circuit built in the reader. During the
repetition, when it has been detected that the chip ID code
received by the chip matches the ID code unique to the device, the
chip converts information from the sensor to sensed data and
transmits the sensed data through magnetic flux generated by the
internal coil to the reader. Upon the termination of a sequence of
operation described above, the chip ID compare circuit is
referenced and looked up. If another chip ID code is fund, the
above sequence of operation is repeated for the found chip ID code.
In this way, the sequence of operation is repeated until the
sequence of operation is completed for all chip ID codes stored in
the chip ID compare circuit. According to the present embodiment,
if the reader operator wishes to get a plurality of items of
information, the reader can selectively acquire only the relevant
data from the chips which are sensing the information that the
reader operator wishes to get. In other words, even if a plurality
of chips are used, the reader can identify specific data that the
chips have, such as measurements taken by the sensors of the chips,
from the chips' ID codes, and can acquire the data selectively.
When a plurality of chips which are appointed to detect different
chemical reactions corresponding to the items of data are situated
in place together to measure liquid samples, the reader can
immediately check the items of data and time to be taken for the
measurement system to take measurements can be shortened.
[0051] [Embodiment 6]
[0052] A still further preferred embodiment will be described,
referring to FIG. 6. FIG. 6 is a schematic diagram showing a reader
configuration in a measurement system of the present invention. The
reader comprises an oscillator block 107, a communication control
circuit block 103, a modulator block 117, an output amplifier block
116, a coupling circuit block 115, a matching circuit block 114,
and external coil 105, an input amplifier block 118, a demodulator
119, and a peak detection and output control circuit block 120.
[0053] When current I flows across a coil having a radius R and N
turns of windings, magnetic field strength at a point at a distance
x from the center of the coil is expressed by the following
equation (Equation 1) (for example, Non-Patent Document Cited). 1 H
= I N R 2 2 ( R 2 + x 2 ) 3 [ Equation 1 ]
[0054] The above equation is true in the near field, that is, a
region where x<.lambda./2.pi. with regard to wavelength .lambda.
corresponding to frequency. If the chip is designed with distance x
between the external coil of the reader and the internal coil of
the chip being 2 mm, which is a normal value, and if x becomes 0.5
mm, magnetic field strength sensed by the coil of the chip becomes
64 times as much as a design standard value. When electric power
far exceeding the design value is generated in the chip, there is a
possibility of breakdown of the power regulator and rise in the
chip temperature. Voltage tolerance of a chip depends on the LSI
process for forming the circuitry on the chip. Voltage tolerances
for sections of the device such as semiconductor pn junctions,
source-drain sections of MOS transistors, gate insulation layers,
sections between two wiring conductors are designed to meet
required standard values. Changing the LSI process to enhance the
voltage tolerances leads to a great increase in cost.
[0055] The above problem can be solved by detecting a peak voltage
of input signals and controlling the output as shown in FIG. 6. The
reader output is controlled, according to the strength of signals
from the chips, so as to avoid chip breakdown and prevent
temperature rise. Thus, output can be set to accommodate various
conditions of measurement almost without changing the chip
design.
[0056] [Embodiment 7]
[0057] A yet further preferred embodiment will be described,
referring to FIG. 7. FIG. 7 is a schematic of a measurement system
application example to a plant, featuring a function of wirelessly
measuring liquid conditions in a pipe, using chips installed inside
the pipe and a reader installed outside the pipe. When liquid
conditions in a pipe are measured by a conventional sensing system,
lead wires are necessary to draw out sensing signals outside the
pipe. As a means of lead taps, sealed through-hole electrodes are
used. However, such problems may occur as leakage from the sealed
electrodes, impurity incursion, and the electrodes cause stagnation
of fluid flowing through the pipe. For example, when a plurality of
items are measured or when many sensors are used to measure liquid
distribution, lead tap structures become complex, which causes
decrease in reliability and cost increase. According to the present
embodiment, conditions inside the pipe can be monitored in a
non-contact and wireless manner. Moreover, this system can be
provided in a simple structure and at a low cost. Because the
reader and chips which have been described in the foregoing
embodiments are used, digitized sensed data from raw data detected
by the sensors of the chips inside the pipe and the result of chip
ID code comparison with the ID number retained by the chip ID
retaining circuit are transmitted through the communication control
circuit to the reader outside the pipe. By obtaining corresponding
between a chip ID number and chip location information beforehand,
conditions in any given position inside the pipe can be monitored
wirelessly. To stabilize communication between the reader and the
chips, it is required that the chips have a constant resonance
frequency. However, due to variation in manufacturing the chips and
depending on the circumstances where the chips are installed, for
example, solution which flows through the pipe and for which
measurements should be taken, other chips or reaction containers
exist around a chip, it is inevitable that the resonance frequency
varies per chip. Resonance frequency difference due to variation in
manufacturing the chips can be adjusted to a predetermined
resonance frequency by trimming the capacitance of an individual
chip. However, trimming increases the chip cost and is ineffective
for resonance frequency variation depending on the circumstances
around an individual chip. Therefore, the RF interface of the
reader should be provided with a frequency variable function. Using
this function, the frequency of the oscillator is varied to adjust
the carrier frequency to the resonance frequency of the chip to
communicate with during measurement, so that the communication can
be stabilized. According to this method, the trimming for adjusting
the resonance points of the chips is unnecessary and, therefore,
costs can be saved. Also, it is possible to dynamically accommodate
resonance point shifts occurring, depending on the surroundings of
the chips.
[0058] As concrete embodiment, the chips 250 are attached to the
inside walls of the pipe 252 and communicate with the reader 261
via a coil 260 outside the pipe. The thickness of the chips is
substantially equivalent to the thickness of a silicone
semiconductor substrate and the chips 1-mm thick or thinner can be
produced. As for the material of the pipe, the walls 252 to which
the chips are installed should have less conductivity, as shown in
FIG. 8, so that the efficiency of electromagnetically coupling of
the chip's coil and the reader's coupling can be enhanced and
communication characteristics can be improved.
[0059] FIG. 8 shows a configuration example for enhancing the
communication efficiency of the present embodiment. Stainless pipes
are widely used for piping in plants because they are excellent in
corrosion resistance, strength, and reliability. However, stainless
pipes are highly conductive and may cause trouble in communications
environment. FIG. 8 explains a pipe structure in which conventional
material is used as much as possible and material capable of
enhancing communication efficiency is introduced only in places
where such material is necessary. The pipe 252 inside which the
chips are installed is made of basically the same material as other
pipe portions 251 where the chips are not installed and minimum
necessary through holes 257 are provided only in places where the
chips are installed. A part 255 which functions as the passage of
magnetic lines of force and has core material 256 which is of high
permeability, that is, allowing magnetic lines of force to pass
through it easily and in which eddy current hardly occurs is
inserted in each through hole 257. Even if the same material as
used conventionally, for example, stainless is used as the material
258 of the pipe inside which the chips are arranged, the
measurement system of the present invention can be applied.
[0060] [Embodiment 8]
[0061] A still further embodiment of the present invention is shown
in FIG. 9. In the measurement system of the present invention, the
communication between the chips and the read is principally
performed in a passive mode; that is, the chips have no power
supply and required electric power is supplied by RF carriers from
the reader. The passive mode is very effective for downsizing the
chips and curtailing costs, but its communication range is limited.
Embodiment 8 provides a method for extending the communication
range effectively. As the reader which drives the coil outside the
pipe, a reader 263 is used which includes a long-range
communication function via an antenna 64 added to the reader 261
which is shown in FIG. 10, and data communication is performed via
an antenna 265 and a transmitter/receiver (transceiver) 266
connected to an external control device 262. This system makes it
possible to monitor conditions inside many pipes which are located
in remote places in a non-contact manner. FIG. 10 shows an example
of application of the system of FIG. 9 to synthetic reaction baths.
In FIG. 10, reference numeral 260 denotes a coil outside the
piping, 264 denotes a transmitter/receiver, 263 denotes a reader,
259 denotes a synthetic reaction bath, and 267 denotes piping.
[0062] Configuration for enhancing the communication efficiency
described for FIG. 8 can be applied in the present embodiment
also.
[0063] [Non-Patent Document Cited]
[0064] Klaus Finkenzeller, RFID HAND BOOK: 1999, John Wily &
Sons Ltd.
* * * * *